Glossary safe machinery 

A device whose sensing function is performed by opto-electronic emitting and receiving elements detecting the interruption of optical radiations generated, within the device, by an opaque object present in the specified detection zone.
(IEC/TS 61 496-2, CLC/TS 61 496-2) In DIN EN 692 “Mechanical presses”, EN 693 “Hydraulic presses” and EN 12 622 “Hydraulic press brakes” the abbreviation AOS is used as a synonym for AOPD.

Device with a sensor function produced by opto-electronic sender and receiver elements,that detects the diffuse reflection of light, generated by the device, by an object in a defined two-dimensional protective field (IEC/TS 61 496-3,CLC/TS 61 496-3).

Number of cycles after which a dangerous failure has occurred on 10 % of the components (for pneumatic and electromechanical components).

>>IFA

Common cause failure: failure of various units due to a single event where these failures are not caused by each other.

European Committee for Electrotechnical Standardisation. Responsible for the harmonization of electrotechnical standards within the European Union and the entire European Economic Region. >>http://www.cenelec.eu/

Prefix for standards adopted by CENELEC.

 Diagnostic coverage: measure of the effectiveness of the diagnostics that can be determined as the ratio of the failure rate for the detected dangerous failures to the failure rate for the total dangerous failures.

Mean operating time in days per year.

Electrical, electronic & programmable electronic safety-related systems
(IEC 62 061/EN 62 061).

Means by which the electro-sensitive protective equipment (ESPE) monitors the state of control devices which are external to the >>ESPE
(IEC 61 496-1/EN 61 496-1). The use of EDM is not limited on ESPE.

European free trade association, an international organisation founded by European states.

Ability of an item of equipment to work satisfactorily in its electromagnetic environment and at the same time not to excessively interfere with this environment, in which there are other items of equipment.

Assembly of devices and/or components working together for protective tripping or presence-sensing purposes and comprising as a minimum (IEC 61 496-1/EN 61 496-1):

• a sensing device
• controlling/monitoring devices
• output signal switching devices (OSSD)

They are used to protect people at machines and systems on which there is a risk of injury. They cause the machine or system to adopt a safe state before a person can be exposed to a hazardous situation.

Failure rate in 10–⁹ hours. >>λ = 1 x 10^-9/h

Failure mode and effects analysis. Procedure for the analysis of effects derived from faults (IEC 812/EN 60 812).

Part of the overall safety related to the machine and the machine control system that depends on the correct function of the >>SRECS, on the safety-related systems in other technologies and on the external features for risk reduction.

Ability to continue to perform a required function in the presence of faults or failures (IEC 62 061/EN 62 061).

Mean operating time in hours per day.

Institute for Occupational Safety and Health of the German Social Accident Insurance. Up until 2009 BGIA.

An interlocking device is a mechanical, electrical or other device the purpose of which is to prevent the operation of a machine element under certain circumstances.

>> λ

 An AOPD with a resolution ≤ 116 mm

Calculated distance between the safeguard and the hazardous area necessary to prevent a person or part of a person reaching the hazardous area before the termination of the dangerous machine function.

Expectation of the mean time to dangerous failure (ISO 13 849-1/EN ISO 13 849-1).

Temporary automatic suspension of one ore more safety function by safety-related parts of the control system (IEC 61 496-1/EN 61 496-1).

Normally Closed
N/C contact

Normally Open
N/O contact

d_op    

>>Is the mean operating time in days per year. 

h_op

 >>Is the mean operating time in hours per day.

t_cycle

>>Is the mean time between the start of two sequential cycles of the part in
seconds per cycle.

Mean probability of a dangerous failure per hour (1/h).

Discrete level used to specify the ability of safety-related parts of control systems to perform a safety function under foreseeable conditions
(ISO 13 849-1/EN ISO 13 849-1).

Positive opening on switches signifies that there must be positive, shape-based transmission of force between actuator and switching element. The actuating mechanism must be so designed that even on mechanical failure, e.g. on the fracture of a spring or contact welding, the contacts open reliably and remain open in the actuated state (IEC 60 947-5-1/EN 60 947-5-1).

Secondary protective device for machinery/systems that can be accessed from the floor and on which the system must be prevented from starting while the operator is in the interior (safety function: preventing start).

The area in which the test object specified by the manufacturer is detected by the item of electro-sensitive protective equipment (ESPE).

• Safety light curtain: The protective field lies between the sender unit and receiver unit. The field is defined by the protective field height and the protective field width.
• Safety laser scanner: The protective field secures the hazardous area on a machine or vehicle. The field is defined by the scanning range, scanning angle, response time and resolution of the device used (see technical specifications).

The limit for the sensor parameter that causes the item of electro-sensitive protective equipment (ESPE) to trigger. It is defined by the manufacturer.

Time by which the response of the contacts is delayed. The times can be adjusted on switching devices with response delay.

The maximum time between the occurrence of the event that caused the triggering of the sensor and the achievement of the off state at the output switching elements (OSSDs).

Placing the machine back in operation. After the triggering of the protective function or after a fault, the protective device can be reset to make it possible to subsequently restart the machine.

Means of preventing automatic restarting of a machine after actuation of the sensing device during a hazardous part of the machine operating cycle, after a change in mode of operation of the machine, and after a change in the means of start control of the machine (IEC 61 496-1/EN 61 496-1).
-Operating modes include: inching, single stroke, automatic
-Start control equipment includes: foot switch, two-hand control, single break PSDI triggering or double break PSDI triggering by the ESPE’s sensor function
-Restart interlock (RES):
The machine stops and the restart interlock (RES) is engaged on interruption of
at least one light beam. This interlock ensures that the machine can only be
restarted if the light path is clear and the reset button has been pressed and
released again.

Function of a machine whose failure can result in an immediate increase of the
risk(s) (EN ISO 12 100-1). A safety function is provided by safety-related parts of control systems (SRP/CS).

The part of a safety function that is provided by a safety-related sub-system (e.g. actuator) for risk reduction.

The limit for the sensor parameter defined by the manufacturer that causes the
item of electrosensitive protective equipment (>>ESPE) to trigger.

Fraction of the overall failure rate of a subsystem that does not result in a dangerous failure (IEC 62 061/EN 62 061).

Discrete level (one out of a possible three) for specifying the safety integrity
requirements of the safety-related control functions to be allocated to the
>>SRECS, where safety integrity level three has the highest level of safety integrity and safety integrity level one has the lowest (IEC 62 061/EN 62 061).

Safety integrity level claim limit (for a subsystem): Maximum SIL that can be
claimed for a >>SRECS subsystem in relation to architectural constraints and systematic safety integrity (IEC 62 061/EN 62 061).

This operating mode is advantageous if parts must be manually inserted or removed periodically. In this mode the machine cycle is automatically re-initiated
after the protective field becomes clear again after one or two interruptions.
The reset device is to be operated under the following conditions:

• on machine start
• on restart if the >>AOPD is interrupted during a dangerous movement
• to initiate a restart after a period of more than 30 s (cf. IEC 61 496-1/EN 61 496-1)
  >>Further information EN 692

Nevertheless, it is necessary to check that the operator cannot be placed at risk during the working process. This situation limits use to small machines on which the hazardous area cannot be entered and there is point-of-operation protection. All other sides of the machine must also be protected using suitable measures. If this operating mode is used, the resolution of the AOPD must be less than or equal to 30 mm (cf. EN ISO 13 855, also EN 692, EN 693).
In general the following errors must be excluded when mounting protective
devices: reaching over, reaching under, reaching around, standing behind.

Electrical control system for a machine the failure of which will result in an immediate increase in the risk or risks.

Part of a control system that responds to safety-related input signals and generates safety-related output signals (ISO 13 849-1/EN ISO 13 849-1).

Limit for the operating time of a component. Mean time until a dangerous failure
has occurred on 10 % of the components.

The MTTFd determined for components subject to wear only applies for this time.

An opaque cylindrical element used to verify the detection capability of the active opto-electronic protective device (AOPD) (IEC/TS 61 496-2, CLC/TS 61 496-2).